Your condition in a Branch is basically testing if number 0 is less then 100 which is always the case. I imagine you want to check if the stamina is lower then 100. In that case you should plug in the stamina variable as the first argument in ‘<’ node.
That should stop the stamina from going over 100.
Not to discourage you from creating something but you might want to check out Timers and how they work. It can get resource expensive running everything on tick.
Keep it up!